Toyohashi University of Technology

About: Toyohashi University of Technology is a education organization based out in Toyohashi, Japan. It is known for research contribution in the topics: Thin film & Fracture toughness. The organization has 7649 authors who have published 12406 publications receiving 192005 citations. The organization is also known as: Toyohashi Gijutsu Kagaku Daigaku & Toyohashi Tech.

Mechanical properties of biomedical titanium alloys

Abstract: Titanium alloys are expected to be much more widely used for implant materials in the medical and dental fields because of their superior biocompatibility, corrosion resistance and specific strength compared with other metallic implant materials. Pure titanium and Ti–6Al–4V, in particular, Ti–6Al–4V ELI have been, however, mainly used for implant materials among various titanium alloys to date. V free alloys like Ti–6Al–7Nb and Ti–5Al–2.5Fe have been recently developed for biomedical use. More recently V and Al free alloys have been developed. Titanium alloys composed of non-toxic elements like Nb, Ta, Zr and so on with lower modulus have been started to be developed mainly in the USA. The β type alloys are now the main target for medical materials. The mechanical properties of the titanium alloys developed for implant materials to date are described in this paper.

Biodegradable polyesters for medical and ecological applications

Abstract: Numerous biodegradable polymers have been developed in the last two decades. In terms of application, biodegradable polymers are classified into three groups: medical, ecological, and dual application, while in terms of origin they are divided into two groups: natural and synthetic. This review article will outline classification, requirements, applications, physical properties, biodegradability, and degradation mechanisms of representative biodegradable polymers that have already been commercialized or are under investigation. Among the biodegradable polymers, recent developments of aliphatic polyesters, especially polylactides and poly(lactic acid)s, will be mainly described in the last part.

Recent metallic materials for biomedical applications

Abstract: Metallic biomaterials are mainly used for replacing failed hard tissue. The main metallic biomaterials are stainless steels, Co-based alloys, and titanium and its alloys. Recently, titanium alloys are getting much attention for biomaterials. The various kinds of new high strength α+β and low-modulus β-type titanium alloys composed of nontoxic elements, such as Nb, Ta, Zr, etc., are developed for biomedical applications because of the toxicity of alloying elements and lack of mechanical biocompatibility of conventional titanium alloys, such as Ti-6Al-4V. Recent research and development in other metallic alloys, such as stainless steels and Co-based alloys, also will be discussed.

Poly(lactide) Stereocomplexes: Formation, Structure, Properties, Degradation, and Applications

Abstract: Summary: Poly(lactide)s [i.e. poly(lactic acid) (PLA)] and lactide copolymers are biodegradable, compostable, producible from renewable resources, and nontoxic to the human body and the environment. They have been used as biomedical materials for tissue regeneration, matrices for drug delivery systems, and alternatives for commercial polymeric materials to reduce the impact on the environment. Since stereocomplexation or stereocomplex formation between enantiomeric PLA, poly(L-lactide) [i.e. poly(L-lactic acid) (PLLA)] and poly(D-lactide) [i.e. poly(D-lactic acid) (PDLA)] was reported in 1987, numerous studies have been carried out with respect to the formation, structure, properties, degradation, and applications of the PLA stereocomplexes. Stereocomplexation enhances the mechanical properties, the thermal-resistance, and the hydrolysis-resistance of PLA-based materials. These improvements arise from a peculiarly strong interaction between L-lactyl unit sequences and D-lactyl unit sequences, and stereocomplexation opens a new way for the preparation of biomaterials such as hydrogels and particles for drug delivery systems. It was revealed that the crucial parameters affecting stereocomplexation are the mixing ratio and the molecular weight of L-lactyl and D-lactyl unit sequences. On the other hand, PDLA was found to form a stereocomplex with L-configured polypeptides in 2001. This kind of stereocomplexation is called “hetero-stereocomplexation” and differentiated from “homo-stereocomplexation” between L-lactyl and D-lactyl unit sequences. This paper reviews the methods for tracing PLA stereocomplexation, the methods for inducing PLA stereocompelxation, the parameters affecting PLA stereocomplexation, and the structure, properties, degradation, and applications of a variety of stereocomplexed PLA materials.

Design and mechanical properties of new β type titanium alloys for implant materials

Abstract: Pure titanium and Ti–6Al–4V alloy have been mainly used as implant materials. V-free titanium alloys like Ti–6Al–7Nb and Ti–5Al–2.5Fe have been then developed because toxicity of V has been pointed out. Al- and V-free titanium alloys as implant materials have been developed. Most of them are, however, α+β type alloys. β type titanium alloys with lower moduli of elasticity and greater strength have been developed recently. Design of new β type titanium alloys composed of non-toxic elements like Nb, Ta, Zr, Mo or Sn with lower moduli of elasticity and greater strength were, therefore, studied based on the d-electron alloy design method, and the basic mechanical properties of designed alloys of button ingots melted by tri-arc furnace in the laboratory were investigated in this study. β type alloys, Ti–Nb–Ta–Zr, Ti–Nb–Ta–Mo and Ti–Nb–Ta–Sn system alloys designed in this study are expected to have greater performance for implant materials. The Young's moduli of these alloys are lower compared with that of Ti–6Al–4V ELI which has been used as an implant material. The alloys on which some heat treatments have been conducted offer suitable tensile properties as implant materials. The tensile strength and elongation of designed alloys in this study are equivalent or greater than required values already reported.